Classifying Shapes Using Tangrams

Since our geometry unit is so full of vocabulary, I am always looking for ways to have students apply the vocabulary to new situations. After learning how to make our own tangrams yesterday, we took it to another level today. We decided to sort and classify the shapes that make up the tangrams. Because we’ve spent a few days describing two types of polygons: triangles and quadrilaterals, we had some really nice anchor charts up on the wall.

Their task today was to classify and describe the shapes from their tangrams using sides and angles. This meant that some of their shapes could be described in more than one way. This was a really cool opportunity for students to participate in math talk, and it was even better to see them using the anchor charts we made together:

Classifying Triangles

The student on the right is trying to classify his triangle by looking at angles.  The student on the left quickly realized that he was holding a shape with four sides.

Classifying Quadrilaterals

This student is checking to see if all four of her sides are equal, as well as if there are four right angles in her shape.

There is nothing better in a math class than hearing students argue over whether something is a right angle or not. Hearing words being used authentically was really cool, especially since they could actually touch and manipulate the shapes! I’ve really taken geometry a long way since I started teaching (ahem…I used to use worksheets only…please don’t judge me!), and the terms and vocabulary has started to stick because of it.


How to Make Your Own Tangrams

There is nothing better than a really good hands on activity in math.  It beats worksheets every time.  It has taken me several years to figure out how to make hands on learning meaningful, not just hands on activities for the sake of not doing a worksheet.

One thing I’ve tried out is having students make their own tangrams.

How to Make Tangrams

All you need to make your own tangrams is paper and a pair of scissors. (Oh, and a little patience.)

The first year I did this, I will not lie to you, it was HAIRY.  Really bad. Like…kids cried because they were so lost during the steps.  I was running around like a chicken with my head cut off trying to help. It was terrible and I vowed never to do it again. Then YouTube happened to the internet…and my world was opened to the idea of using video to help me teach how to make them. In addition, I have them sit in groups so that they can help each other when they are stuck on a step. Things have improved dramatically.

Here are two videos that I’ve used in the past for my third graders. I personally like the first one better, but it’s a bit long.  The second one is short and sweet and to the point.

After we make the tangrams, I have them set all the pieces in front of them and set the timer for five minutes.  I tell them that they have five minutes to put them back together into the square they started with.  ONE third grader in the last 7 years has been able to do it in five minutes! Of course every year it is very dramatic since hardly anyone belongs to that Hall of Fame.  When I start the timer the room becomes so silent, you could hear a pin drop. It is instant engagement.

My favorite part is that during the process of making them, they find shapes they know and you hear them shout things like “trapezoid!”, or “parallelogram!”. This all leads perfectly to the next activity, which I will talk about in my next blog post where I take them a bit deeper.